Question for Jim Colt - Purpose of 2 fine cut charts

[tony506]

Hi Jim,
Question on the powermax 65 manual.
It shows 2 cut charts for using the fine cut nozzle assemblies, the regular and slow cutting speeds.
What is the purpose of this? The amp settings look about the same for both, just the ipm settings vary, so I can't get my head around how they can cut at such different speeds.
What chart would be best to use with the 65 on a plasmacam machine?
Tony

[Marty]

Jim will probably comment as well, but here is an old thread where the subject was discussed before....http://www.plasmaspider.com/viewtopic.php?f=4&t=10385

Marty

[jimcolt]

Many low cost cnc machines cannot cut well at speeds above 150 ipm. Per these users requests we worked in our development labs in NH and developed a set of cut specs for under 150 ipm. The high speed charts provide the best productivity and cut quality if your machine is stable at these speeds.

If you have a PlasmaCam with advanced Design Edge software and advanced height control then you should use the high speed cut charts.

Jim Colt Hypertherm

Hi Jim,
Question on the powermax 65 manual.
It shows 2 cut charts for using the fine cut nozzle assemblies, the regular and slow cutting speeds.
What is the purpose of this? The amp settings look about the same for both, just the ipm settings vary, so I can't get my head around how they can cut at such different speeds.
What chart would be best to use with the 65 on a plasmacam machine?
Tony

[tony506]

Thanks Jim,
I have been cutting 16g HRS sheet.
I have tried using the higher speeds and sometimes it works, but a lot of the time I am getting dross blowback and it don't seem to cut right through.
Checked grounding, changed tips, nozzles etc. Air is dry, I have it running through a heated dryer and then through decassiant filter. Pressure at inlet to HP60 is about 100-110psi. I changed the speeds from 250 incrementally about 20-30ipm, up and down.
I called plasmacam and they got me to check auto zero arc voltage and when that didn't work, told me the 250ipm was to fast and told me to cut down to150ipm. I get a good cut at 170ipm.
I am really curious as to what may be doing this.
I have attached a pic of the cuts at the 250ipm setting.
Can you suggest anything?
Thanks
Tony

[jimcolt]

Most likely the torch is running too high off the plate. Make sure it is at .060" (regardless of what you set it at....look at it or measure it). If too high the FineCut consumables will not cut through. The speeds in the cut chart are correct, if height is too high, slowing down will work, but cuts will be drossy.

Jim Colt Hypertherm

[Metriccar]

Tony, I made some lines showing what cut path the torch is taking on the corners. Instead of cutting perfectly sharp 90 degree angles, the torch wonders and vibrates around the corners. The only solution is to slow the machine down or decrease acceleration.

This seems to be a common theme among tables in the "low dollar" range. I haven't seen one that doesn't do it yet.

100_1927.JPG

The only solution I see is to use the "low speed fine cut" settings. It would be nice if I could use the high speed fine cut charts. But instead I have to slow the machine down and deal with the dross.

As for not cutting through at 250 IPM if that is book setting, the only other thing I could think of it being is amp setting.

[tony506]

Thank you fella's,
I am learning new things all the time.
I am sure the torch height is correct, but I will double check.
If that is so, I will just use the slower speeds. Thats not a problem, just wanting to try and learn what I can about this kit.
Tony